Diaphragm for gas meters



Aug. 24 1926.

- 1,597,237 F- M DONALIJ DIAPHRAGM FOR GAS METERS Filed June 9 92 liiiiiiiiiil'l'f' 77 INVENTOR 7W4 C 0% 06 ATTORNEY Patented Aug. 24, 1926.

'UNITED STATES PATENT OFFICE.

FREDERICK MCDONALD, OF ALBANY, NEW YORK, ASSIGNOR T0 AMERICAN METER COMPANY, INCORPORATED, OF NEW YORK,,N. Y., A CORPORATION OF DELAWARE,

DIAPHRAGM FOR GAS METERS.

Application filed June 9, 1923. Serial No. 644,513.

The present invention relates to an improvement in diaphragms for gas meters and more particularly tothe construction of the membrane portion thereof which is com monly referred to in the art as the diaphragm leather. At the present time and, so far as applicant is informed, for many years past, diaphragms for some types of gas meters have included as elements of their construction two or more spaced frame members to which is secured a suitable menu brane or membrane-like member of flexible material such as tanned lamb skin, this being the particular material which has been found most satisfactory in use over a'period of many years. Manufacturing conditions make it practically essential that these leathers be made up of two or more'separate pieces having their ends sewed and cement ed together in overlapping relation to pre vent leakage at the joints. Leakage through the pore openings of the lamb hide or skin is commonly overcome bythe use ofpore filling liquids such as certain kinds of oils well known in the art. This,however, does not entirely eliminate leakage in the vicinity of the overlapping portions of seams even where the pieces are cemented together by shellac and then sewed in the most effective manner. y 1 V A longv series of tests has revealed the fact that somewhere between twelve and fifteen per cent of all seams thus cemented and sewed will produce at least one small puncture which. is, of course, sufficient to render the membrane defective. This means that the defective seams must be cut out of the material and new membranes made from the salvaged pieces, resulting not only in a waste of material, but also in a greater waste of time and labor. Heretofore it has been customary, in the manufacture of diaphragms, to secure the leather to the frames with the hair surface or side exteriorly' exposed -and the opposite or flesh side interiorly exposed, or vice versa, so that, in se curing component pieces together a portion of the flesh side of one piece is in contact with and secured to a portion of the hair side of the other piece.

When these pieces are sewed together by felling stitches the needle passes through both sides of one piece but through only one side of the opposed piece. In practice, it happens that the needle either punctures the second side of said opposed piece or makes an opening which communicates with a pore in said piece, thus producing a leak. I have discovered that the number of openings or leaks produced in sewing can be materially reduced if the parts to be sewed together are arranged with the flesh side of one piece engaging the flesh side of the other. lVith this arrangement the needle pierces both sides of one piece as heretofore but does not penetrate the hair side of the opposed or contiguous piece. Very extensive tests of diaphragms having the pieces sewed together in this manner indicate only four tenths per cent of defective seams. While the beneficial results of sewing the pieces togther with the flesh side of one piece con-- tiguous with the flesh side of the other piece are very marked, the reasons therefor are as yet obscure. One theory in explanation of the phenomenon is that the layer exposing the hair side of the skin is of closer texture than that exposing the flesh side, and that in any given skin the cross sectional layer or increment of close or relatively impervious texture is substantially thinner than the remaining layer or increment exposed on theflesh side. Thus, a needle penetrating the relatively thin impervious layer may frequently make anopening which communicates 'w'ith the relatively porous layer without passing entirely through said layer, thus forming a minute passageway causing leakage at that point. However, leakage is less likely along a seam in which the needle passes through only one increment of close texture rather than through the close texture layers of both pieces as is the case in the present practice. So much for my invention in so far as it relates to the prevention of initial leaks or perforations in the diaphragm membrane.

Long experience in the gas meter art indicates that leaks frequently develop in use along the seams of the diaphragm apparently by reason of the stiffening or hardening of the shellac which causes the leather to crack when flexed. The choice of adhesives is limited considerably by the charof membranes including shellac cement been necessary to accept the lesser evil of eventual hardening and cracking as compared with the greater evil of chemical or other reaction between the gas the adhesive which would result in a much speed ier deterioration of the diaphragm. I have discoveredthat a solution of nitrocellulose nd amyl acetate when applied to the joint between the pieces of skin making up the diaphragm leather produces an effective and seemingly permanent bond. unaffected by conditions ordinarily encountered in the use of gas meters. This adhesive, besides being unaffected by theingredients ot the gas, appears to retain its flexibility to such an extent that crzcking of the leather in ope tion of the diaphragm is reduced to a mini mum, thus more fully meeting the uirements of practical conditions of operation by extending the period of eifective use oi? the device. Furthermore, I ha *e also found that the employment of the nitrocellulose. adhesive, particularly where the pieces. of leather are joined flesh side to flesh side, gives the resulting membrane a composite tensile'strength materially greater than that joints. Extensive tests with a. commonly used gradeof lamb skin indicate that'tae shellac joint separates at about seventy pounds pull, whereas the nitrocellulose cemented joint is at least as resistant to break ing under pulling pressure as the material itself, thus indicating that the character of the bond between the pieces of leather when made by means of nitrocellulose is materially, differentfrom the character of the bond formed when shellac is used. It is contemplated that .under some circumstances the use of the nitrocellulose cementmay rcn der sewing of the joint unnecessa'ryj This has never been possible in the gas meter art where shellac or other known adhesives have been used on account of the rela Lively insecure character of the joint and the tendency of the shellac to cause craci-zing of the i leather, for that reason rendering necessary a supplementary fastening expedient in the form ofsewmg. Obviously, the combina- 7 tion of the nitrocellulose cement and the sewing without penetration of both incre- V nieuts of hair side'produces peculiarly effectivejoint'or seam for the particular use indicated.

'My invention will be better understood by reference to the drawings illustrating one embodiment thereof, which form a part of the present specification, and in Which Figure 1 is a view in perspective of a gas meter diaphragm, and

Figure 2, a section on the line 2--2 of Figure 1.

The drawings disclose a diaphragm construction including spaced supports or frames 1 and 2 to which is secured membrane madeup of two separate pieces of lamb skin 3 and 4, the peripheral edges of saidpieces being fastened to'the frames by means of windings 5 and 6, respectively. As

incicated more clearly in Figure 2, thesep-i arate pieces 3 and it have their end poit1ons mutually overlapping with the flesh side 7 of the piece 4: opposed to the flesh side 8 of the piece 3, said opposed portions 'beingheld together by a suitable adhesive 9, preferably a solution of nitrocellulose and amyl acetate. T he joint thus formed is made more secure by means of rows of st-itching including stitches 10, said stitches avoiding penetration of both incrementsof'hair side 11 and 1:2 along given line of stitching. Although it have shown the seams orjoin ts with the stitch reinforcement, it is contemplated that under some circumstances, this reinforcement may be dispensed with on account of the etlective bond ail'orded by the particular preferred adhesive hereinabove referred to. I

The illustrated embodiment of my inven tion shows the useof two separate pieces of skin. lt'will'be obvious that a similar re sult may be accomplished by using a greater number of pieces, for. example, four or six, the essential feature so far as the numberof pieces is concerned, being to provide an even number so that it maybe possible at every joint to have the flesh side of one end portion opposed to the flesh sideo'f the neat adjacent end portion,

I claim as my invention: 7

A membrane for-gas meter diaphragms comprising a plurality of pieces of leather arranged with end portions of the flesh side surface of one piece overlapping and adhesively secured to end portions of the flesh side surface of the adjacent piece, each piece having a series offelling stitches passing therethrough and engaging a conti uous portion of said adjacent piece without passing through thehairi side thereof. In testimony whereof, I have signedniy name to this saecification this 7th day of 

